The invention relates to a packaging container comprising a multi-layer composite material of metal and synthetic plastic foils having a wall in which a weakening score line defines a tear-open part and in which a starting region of the tear-open part is punched free. A small plate, which covers the punched-open starting region is tightly sealed to the inside of the wall of the container.
A tear-open container made known, for example, by the German Offenlegungsschrift 2,250,594, has a multilayer cover whose outer layer is a metal foil from which the cover derives its rigidity and tightness. The inside of the metal layer is covered with a synthetic plastic layer whose purpose is to prevent corrosion of the metal by the contents of the container. To facilitate opening the container, the cover has a tear-open portion defined by a weakening score line and is also equipped with a specially formed lever of rigid material which is fixedly attached to the starting portions of the tear-open part. The lever is attached to the cover with a rivet which is formed integrally out of the material of the cover. However, this method of fastening the lever can be used only with a cover material whose metal layer has a certain minimum thickness and rigidity.
Also known are so-called semi-rigid containers or lightweight containers which are deep-drawn out of a thin, metal-plastic composite material into the shape of a dish, and which have an edge flange to which a cover made of the same metal-plastic composite material is welded. The metal-plastic composite material usually consists of an aluminum foil of a thickness of 0.08 mm to 0.2 mm to which a polypropylene foil of a thickness of 0.015 to 0.05 mm is glued. These containers, which are very handy and appealing, are opened by cutting open the cover within the welding bead or by pulling the cover off, whereby the welding bead is peeled apart. Pulling the cover off in this manner is possible only when the plastic layer is very thin, which reduces the reliability of the seal.